Chemical Reaction
3H2(g)  +    N2(g) ------>  2NH3(g)
3 mol H2 (reactant) = 1 mol N2 (reactant)  consumed
3 mol H2 (reactant) =  2 mol NH3 (products) produced
1 mol N2 (reactant) = 2 mol NH3 (products) produced
3 x 2 (6) g H2 (reactant) = 1x 28  (28)mol N2 (reactant)  consumed
3 x 2 H2 (6) (reactant) =  2x 17 (34) NH3 (products) produced
1 x 28 (28) g N2 (reactant) = 2 x 17 (34) NH3 (products) produced